Rotary printing press impression cylinder having clamping and sheet gripping devices

ABSTRACT

A printing press of the lithographic type having a pair of blanket cylinders and a cooperating impression cylinder. At least one of the blanket cylinders has, adheringly mounted thereon, a perforation strip presenting a line of regularly spaced perforation projections extending to a constant shallow height from the surface of the blanket. The impression cylinder is provided with a resilient, perforation-inducing covering layer for cooperating with the projections so that when the cylinders rotate together a sheet held by the impression cylinder is penetrated with a line of perforations. In the preferred embodiment of the invention the two blanket cylinders cooperating with the impression cylinder each have perforation strips, extending respectively at right angles to one another, and which successively engage the sheet on the impression cylinder, so that intersecting lines of perforations are produced in the sheet. In accordance with one of the aspects of the invention the impression cylinder is formed with a longitudinal gap or groove having a well defined edge and a recess extending continuously thereunder. The resilient covering layer has a mounting bar at one end which is clamped in the recess, with the covering layer being drawn over the edge of the groove in a tight bend. Mounted at the edge of the groove, adjacent the bend, is a gripper pad bar having a cooperating cyclically operated set of grippers for gripping the leading edges of successive paper sheets. The set of grippers and the gripper pad bar are both mounted in such a way as to permit temporary retraction away from the edge of the groove thereby to provide a radial clearance path for easy removal of the mounting bar and its associated covering layer when the mounting bar is unclamped. This permits rapid substitution of a conventional non-resilient impression blanket upon detatchment of the perforation strips to reestablish the normal printing function of the blanket cylinders.

United States Patent 1191 Preuss Dec. 16, 1975 ROTARY PRINTING PRESSIMPRESSION CYLINDER HAVING CLAMPING AND SHEET GRIPPING DEVICES [75]Inventor: Friedrich Preuss, Sprendlingen,

Germany [73] Assignee: Roland Oifsetmaschinenfabrik Faber & Schleicher,Germany [22] Filed: Aug. 15, 1974 [21] Appl. No.: 497,723

[30] Foreign Application Priority Data Aug. 16, 1973 Germany 2341326[52] U.S. Cl. 101/246; 101/136; 101/409; 101/415.1 [51] Int. Cl. B41F21/04; B41F 29/04; B41F 7/10 [58] Field of Search 101/409, 410, 411,246, 101/226, 227, 224, 415.1; 83/343-659, 679, 495, 698

[56] References Cited UNITED STATES PATENTS 1,545,791 7/1925 Owen10l/415.1 1,579,180 3/1926 Thayer 1 l0l/227 X 1,579,182 3/1926 Thayer 1lOl/227 X 1,582,390 4/1926 Evans l0l/4l5.l 1,686,065 10/1928 Blainel0l/4l5.l 2,089,225 8/1937 Polachek 101/226 2,118,238 5/1938 Smith101/177 2,599,776 6/1952 Peyrebrune 101/409 3,302,490 2/1967 Bishop83/665 x 3,384,014 5/1968 Berg 101/415.1 3,430,560 3/1969 Nettleman83/659 x 3,431,847 3/1969 Smith 61 al 101/226 x 3,587,382 6/1971 Boyd83/698 Primary Examiner-J. Reed Fisher Attorney, Agent, or FirmWolfe,Hubbard, Leydig, Voit & Osann, Ltd.

571 ABSTRACT A printing press of the lithographic type having a pair ofblanket cylinders and a cooperating impression cylinder. At least one ofthe blanket cylinders has, adheringly mounted thereon, a perforationstrip presenting a line of regularly spaced perforation projectionsextending to a constant shallow height from the surface of the blanket.The impression cylinder is provided with a resilient,perforation-inducing covering layer for cooperating with the projectionsso that when the cylinders rotate together a sheet held by theimpression cylinder is penetrated with a line of perforations. In thepreferred embodiment of the invention the two blanket cylinderscooperating with the impression cylinder each have perforation strips,extending respectively at right angles to one another, and whichsuccessively engage the sheet on the impression cylinder, so thatintersecting lines of perforations are produced in the sheet. Inaccordance with one of the aspects of the invention the impressioncylinder is formed with a longitudinal gap or groove having a welldefined edge and a recess extending continuously thereunder. Theresilient covering layer has a mounting bar at one end which is clampedin the recess, with the covering layer being drawn over the edge of thegroove in a tight bend. Mounted at the edge of the groove, adjacent thebend, is a gripper pad bar having a cooperating cyclically operated setof grippers for gripping the leading edges of successive paper sheets.The set of grippers and the gripper pad bar are both mounted in such away as to permit temporary retraction away from the edge of the groovethereby to provide a radial clearance path for easy removal of themounting bar and its associated covering layer when the mounting bar isunclamped. This permits rapid substitution of a conventionalnon-resilient impression blanket upon detatchment of the perforationstrips to reestablish the normal printing function of the blanketcylinders.

1 Claim, 11 Drawing Figures U.S. Patent Dc.16,1975 Sheet10f3 3,926,118

US. Patent Dec. 16, 1975 Sheet 2 of3 3,926,118

U.S. Patent Dec.16,1975 Sheet3of3 3,926,118

ROTARY PRINTING PRESS IMPRESSION QYLINDER HAVING CLAMPING AND SHEETGRIPPING DEVICES As shown in US. Pat. No. 3,224,367, it is known to makea line of perforations in a sheet by means of a perforation wheelpositioned opposite the impression cylinder of a lithograph press. It isalso known to mount a perforation strip, presenting regularly spacedperforating projections, upon an impression cylinder for working againstthe resilient blanket of a blanket cylinder. However, because of thefact that a perforation strip requires a backing of substantial widthfor anchoring purposes, it is impossible, in this way, to secureintersecting lines of perforations. Moreover, the impression cylinder,upon which the perforation strips are secured, is often not readilyaccessible or demountable, and it is difficult to position theperforation strips precisely thereon.

It is the primary object of the present invention to provide aperforation system for a multi-color printing press which involves useof perforation strips, preferably extending at right angles, onrespective blanket cylinders and which cooperate with a specialresilient, perforation inducing covering layer on the impressioncylinder. It is a related object of the invention to provide a novelconstruction of impression cylinder which includes provision forclamping a covering layer, having a mounting bar, in place and which inaddition includes a gripper pad bar and set of cooperating cyclicallyoperated grippers for gripping the leading edges of successive sheets ofpaper, with novel provision for retracting both the grippers and gripperpad bar well away from the covering layer and mounting bar to provideclearance for prompt removal of the mounting bar and covering layer fromthe cylinder, thereby to permit rapid substitution of a covering layerhaving different characteristics for use when the perforation strips areremoved from the blanket cylinder for restoration of the printingfunction.

It is an object of the present invention in one of its aspects toprovide an impression cylinder construction which has a provision fortaut clamping of a covering layer as well as provision for cyclicalgripping of successive paper sheets, for transport, and in which theclamping and gripping means are nested in the same groove in thecylinder without interference between their respective functions, andwith novel provision for rapid substitution of covering layer.

Other objects and advantages of the invention will become apparent uponreading the attached detailed description and upon reference to thedrawings in which:

FIG. 1 is a schematic view multi-color sheet fed rotary printing press,the last printing unit of which is equipped for making of perforations.

FIG. 2 shows the blanket cylinders and cooperating impression cylinderof the last printing unit.

FIG. 3 is a developed view showing the blanket on the upper blanketcylinder of FIG. 2.

FIG. 4 is a developed view showing the blanket on the lower blanketcylinder of FIG. 2.

FIG. 4a shows, in face view, a fragment of the perforation strip used inFIGS. 3 and 4.

FIG. 4b is an enlarged section looking along the line 4b-4b in FIG. 4a.

FIG. 4c is an enlarged cross section looking along the line 4c-4c inFIG. 4a.

FIG. 5 is a fragmentary transverse section taken through the impressioncylinder and looking along the line 55 in FIG. 6.

FIG. 6 is a fragmentary face view corresponding to FIG. 5.

FIG. 7 is an end view of the cam follower mechanism looking along theline 7-7 in FIG. 6.

FIG. 8 is a fragmentary view looking along the line 8--8 in FIG. 7.

While the invention has been described in connection with a preferredembodiment, it will be understood that I do not intend to be limited tothe particular embodiment shown but intend, on the contrary, to coverthe various alternative and equivalent forms of the invention includedwithin the spirit and scope of the appended claims.

Turning now to FIG. 1 of the drawings there is shown a typical printingpress 10 havingthree printing units 11, 12, 13 of the five-cylinder typehaving interconnecting conveyors 14, 15, 16 and terminating in adelivery mechanism 17, the conveyors and delivery mechanism beingconventional and not part of the present invention. Taking the printingunit 13 as typical, it includes an impression cylinder 20 (FIG. 2)having cooperating blanket cylinders 21, 22 which, in turn, haverespective plate cylinders 23, 24. The means for inking and dampeningthe plates on the plate cylinders are not shown and will be understoodto be conventional. The resilient blankets on the blanket cylinders 21,22 are indicated at 31, 32, the blankets being held in place byconventional mounting and tensioning means 33, 34. The blankets areshown in developed form, that is, laid out flat, in FIGS. 3 and 4.

When using the press 10 for conventional printing a paper sheet, fedinto the unit 11, is printed in two colors, then passes to unit 12 forprinting in two additional colors. Following this the sheet istransferred to unit 13 where it is printed in two more colors, making atotal of six.

In accordance with the present invention the third press unit 13 arequickly and easily adapted for perforating the sheet, instead ofperforming a printing function, using perforation strips secured to theblankets 31, 32 of the blanket cylinders and with the normal, relativelyhard, covering of the impression cylinder being replaced by a specialresilient, perforation-inducing covering for cooperating with theperforating projections on the blankets and with the sheet being actedupon successively by the latter.

Thus in carrying out the invention the blanket 31 of the blanketcylinder 21, and which is shown in FIG. 3, has cemented to it a set ofperforation strips 40 arranged in parallel relation. Similarly theblanket 32 on cylinder 22, shown in FIG. 4, has a set of perforationstrips 41 arranged at right angles to the first set; for example, wherethe perforation strips are peripheral on blanket 31, they are axiallyarranged on blanket 32.

To understand the construction of an individual perforation strip 40,reference is made to FIGS. 4a-4c. The strip includes a metal member 43of hard metal but of light flexible construction, in inverted T shape,having a mounting portion 44 and series of spaced, upwardly extendingprojections 45 o shallow height. The length and spacing of theindividual projections 45 depends upon the desired length and spacing ofthe perforations. To hold the perforating element 43 in 3 place upon therubber blanket 31, it is secured on the underside of a strip of tape 46,with the projections 45 projecting through along the center line of thetape, and with the tape being backed by an adhesive layer 47 of a typecapable of sticking to the surface of the rubber blanket.

In accordance with one of the important aspects of the present inventionthe impression cylinder 20, instead of having the usual, relativelystiff covering, or impression blanket, utilized for back up purposes inlithograph printing, and which may be typically made of copper or hardrubber, the impression cylinder is provided with a resilientperforation-inducing covering 50 which may be formed of rubber or aresilient plastic having rubber-like characteristics and of suchdurometer rating as to accommodatingly receive the tips of theperforation projections 45 on the blanket cylinders thereby to cause theprojections to cleanly break through the thickness of the supportedsheet of paper S to form crisp and well defined lines of perforation orweakening. Further in accordance with the invention theperforation-inducing layer 50 is provided at one end with alongitudinally-extending mounting, or reinforcing, bar 51 for purposesof anchoring the covering 50 tautly in place.

Still further in accordance with the invention a groove is formedlongitudinally in the surface of the cylinder for accommodating spacedclamping devices for clamping the reinforcing bar in place and foraccommodating a gripper pad bar as well as a set of cooperating grippersfor holding a sheet on the surface of the cylinder and with provisionfor simultaneous retraction, to a clearance position, of both thegrippers and the gripper pad bar so that, upon release of the clampingdevices, the reinforcing bar and its associated covering layer may beconveniently and quickly removed, and a conventional impression blanketsubstituted, so that, upon removal of the perforation strips, normalprinting may be resumed. The three types of mechanism, and thesupporting means therefor, are mounted in a longitudinally extendinggroove 60 formed in the impression cylinder having a well defined edge61 and a floor 62. Extending longitudinally under the edge, and at floorlevel, is a continuous corner recess 63 which receives the mounting bar51.

For the purpose of clamping the mounting bar in place a plurality ofclamping devices 70 are provided at spaced positions within the groove,but only one of which is shown in FIG. 6. The illustrated device whichmay be referred to as a clamping dog is of L cross section having afirst, or clamping, leg 71 and a second, or supporting, leg 72, with theend of the clamping leg 71 projecting over the edge of the mounting bar51 as shown in FIG. 5. The clamping leg 71 is penetrated by a clampingscrew 73, the lower end of which is threaded into the cylinder body. Forraising the clamping member away from the reinforcing bar when the screwis loosened, is a leaf spring 74, of C shape, nested against the floor62.

By providing a plurality of clamping devices 70 at spaced intervalsalong the groove 60, the intervening space may be utilized forinstallation of sheet gripping mechanism, to be discussed.

At its opposite end the covering layer 50 engages a tensioning bar 75having a clamping strip 76 held by screws 77. Tension is applied innon-retrograde fashion by a worm wheel 78 rotated by a worm 79 (FIG. 6).

Thus in carrying out the present invention there is provided adjacentthe wall-defined edge 61 of the groove, and the resilient layer 50 whichis tightly bent over such edge, a gripper pad bar 80. The bar issupported upon a series of mounts 81, only one of which is shown in FIG.6. Such mount is of L shape having a radially projecting portion 82,which carries the bar at its outer end, and projection 83 extending atright angles thereto. For pivoting the mount, a pivot pin 84 is providednear the junction of the portions 82, 8.3, the ends of the pin beingreceived in alined apertures in the lateral portions of a mounting block85 which is secured to the floor of the groove by means of screws 86.

The projection 83 of the mount is threadedly engaged by an actuatingscrew 86. Turning the screw in a clockwise direction causes the tip ofthe screw to react against the bottom of the groove, thus rotating themount 81 clockwise to bring the gripper pad bar 80 into an operatingposition, illustrated in FIG. 5, closely adjacent the bend in thecovering layer 50.

In order to prevent the gripper pad bar from being advanced too far,which would run the risk of crushing the layer 50, a limit stop in theform of a set screw 87 is provided in a bracket 88. Thus the separateactuating screws 86 in each of the mounts 81 may be turned untiltightening occurs which indicates that the projections 83 have bottomedagainst the respective set screws 87.

For the purpose of cooperating with the gripper pad bar 80, a gripperassembly is provided having a gripper shaft 90 mounting individualgrippers of which four are indicated at 91-94. The gripper shaft isjournaled in bores 95 formed in end members 96, only one of which isshown (FIG. 6). For the purpose of cyclically rocking the gripper shaft90, a rocking mechanism is provided at the end of the shaft in the formof a two-part cam follower device including a follower lever 101 and acooperating adjusting arm 102. The follower lever carries, at its tip, afollower roller 103 which rides against a generally circular cam surface104 on the associated stationary frame structure (FIG. 7). The camsurface is so formed as to rock the cam follower lever 101, and hencethe gripper shaft, on a cyclical basis for opening and closing thegrippers.

To understand the details of the rocking mechanism 100, reference ismade to FIGS. 6-8.,I-Iere it will be noted that the followerlever 101 isreleaseably clamped to the shaft 90 by means of a clamp 105 while theadjusting arm 102 is permanently pinned to the shaft by means of a pin106. Threaded into the arm is an adjusting screw 107 having a tip whichengages the end 108 of the lever 101. For biasing the grippers towardopen position, a spring 109 is secured by a pin 110 to the adjusting arm102, the other end of the spring being anchored to the cylinder by meansnot shown. The cam surface 104 is faced to work against the spring andto provide positive closure of the grippers against the leading edge ofthe sheet S.

In accordance with the present invention means are provided forretracting both the gripper pad bar 80 and the grippers 91-94 to aclearance position to provide radial access for the reinforcing bar 51at the end of the cover 50. In the case of the grippers, this isaccomplished by releasing the clamp 105 which secures the lever 101 toshaft 90. Following this, the gripper adjusting screw 107 is unscrewedwith respect to the arm 102 so that the arm may rock with respect to thelever 101 under the influence of the spring 109, thereby to rotate theshaft 90 in a direction ,to well clear of the gripperpad bar 80.

Subsequently, the actuating screws 86 in the respective bar mounts'S'lare u'riscrewed causing the mounts to rock counterclockwise as viewdinFlGuS, thereby retracting the gripper pad bar80 .well away from the bendof the cover member 50 and providing a clear radial path for the entryand exit of mounting bar 51.

Consequently, upon unscrewing the screws 73, the springs 74 expand,loosening the clamping members 70 so that the mounting bar 51 is free tobe withdrawn outwardly through the aforementioned radial clearancepassage.

This permits prompt and easy substitution of a conventional impressioncylinder blanket having a similar mounting bar. At the opposite ortensioning end the resilient covering layer is disengaged by looseningthe clamping screws 77 on bar 75, and the end of the new swing thegrippers 9 l 94 blanket is substituted. With a new mounting bar recessedin corner 63, the clamping screws 73 are retightened to hold it securelyin place. The bar 75, at the other end, with the new blanket attached,is rotated to the extent necessary to put the blanket under tension.

Following this, the screws 86 on the bar mounting members 81 are turnedtight, causing the gripper pad bar 80 to swing broadwise in a clockwisedirection to the operating position shown in FIG. 5.

Finally, the adjusting screw 107 forming a part of the cam followerassembly is screwed inwardly with the reaction against lever 101 causinggripper shaft 90 to rotate against the force of the spring 109, therebyadvancing all of the grippers 91-94 into normal operating position. Suchposition can be accurately reestablished by calibrating the screw 107 asindicated in FIG. 8 and by providing an arm 107a on the screw whichcooperates with a fixed, but removable stop 107b. The clamp 105 is thentightened to hold the lever 101 in place on the shaft.

This completes restoration of the impression cylinder to the printingmode. Subsequently, when it is desired to perforate the printed product,the procedure is reversed: Perforation strips 40, 41 are secured to therubber blankets 31, 32. The gripper shaft is backed off by looseningclamp 105 and by unscrewing the adjusting screw 107. The gripper pad bar80 is similarly backed off by unscrewing the actuating screws 86.Finally, the clamping screws 73 are unscrewed to release the clampingmembers 70 to permit substitution of mounting bars; clamping screws 73are then tightened, followed by tightening of actuating screws 86 andadvancement of adjusting screw 107.

It will be apparent that the device satisfies the objects of theinvention. By providing two sets of perforation strips at relative rightangles to one another on two different blanket cylinders cooperatingwith the same impression cylinder, intersecting perforations of highquality can be readily achieved. By contrast it is not possible toprovide intersecting perforations where perforating strips extend inrectangular directions on the same cylinder because of the problems ofoverlapping strips at 90, the problem being worsened by the fact thatthe strips are quite wide, because of the attachment area, so that onestrip tends to mask the other at the region of intersection. Mountingthe strips on the respective blanket cylinders is a relatively easymatter since the blanket cylinders are, in most press designs, readilyaccessible. By contrast, the impression cylinder is usually difficult ofaccess. However, notwithstanding 6 this, the present invention providesfor easy and quick substitution of a resilient perforation-inducing.blanket for the relatively non-yielding surface used inthe printing modeThe turning of a few screws between loose andtight positions isvirtually all that is required to substitute a covering layer forperforation purposes,

and this may be done quickly and easily even though the impressioncylinder may not be readily accessible.

The invention disclosed andclaimed herein has general application tomulti-color printing presses of the lithographic type both with respectto new presses and, by modification and substitution of impressioncylinder, presses which are already in the field.

While the invention is primarily concerned with establishing a line, orlines, of perforations in a printed sheet, the invention is equallyapplicable to forming grooves in a sheet, and in particular intersectinggrooves. This may be accomplished by making the perforation projections45 (see especially FIG. 4b) continuous and of slightly less height thanrequired for perforation; consequently the term perforation projectionsshould be understood to include this possibility. Also while theinvention contemplates interchanged substitution of the regularimpression blanket by a resilient covering layer, the invention is notlimited thereto and the regular relatively non-resilient impressionblanket may if desired be permanently mounted on the impressioncylinder. In such event the perforationinducing layer 50 may simply besuperimposed, and held in place by its mounting bar 51 when theperforation function is employed, the blanket cylinders under suchcircumstances being approximately backed off the amount necessary toaccommodate the added thickness.

The term rubber as used herein denotes any tough, resilient, rubber-likematerial.

It is one of the features of the present construction that theperforating strip, in accomplishing perforation, is mounted upon a firstresilient layer, namely, the rubber blanket on the blanket cylinder withthe perforating projections thereof working against a second resilientlayer, namely, the covering layer on the impression cylinder. This isfound to provide an improved result compared to the usual situationwhere the perforating strip is mounted upon a relatively hard andunyielding surface as, for example, the surface of the conventionalimpression cylinder blanket.

What I claim is:

1. In an impression cylinder for a lithograph printing press, thecombination comprising a body having a gap in the form of alongitudinally extending groove having a well-defined longitudinal edgeand a recess extending continuously thereunder, a covering layer havinga rigid mounting bar at one end, clamping means for clamping themounting bar in the recess, means recessed in the cylinder fortensioning the opposite end of the covering layer so that the layer isdrawn into a tight bend over the edge of the groove and thence over thesurface of the cylinder, a gripper pad bar extending continuously alongthe edge of the groove, spaced mounts seated in the groove for mountingthe gripper pad bar and for releasably holding it in a normal positionin which it is snugly adjacent the bend in the covering layer, eachmount being of L shape having a radial portion supportively engaging thegripper pad bar and having a projecting arm portion at right anglesthereto with a pivot at the bend of the L, a gripper shaft in the groovehaving a set of grippers cooperating the gripper pad bar from its normalposition to a position separated from the bend of the covering layer toprovide a clear radial path so that upon loosening of the clamping meansthe mounting bar and covering layer may be removed from the recess clearof the cylinder for replacement by an alternate mounting bar andcovering layer.

1. In an impression cylinder for a lithograph printing press, thecombination comprising a body having a gap in the form of alongitudinally extending groove having a well-defined longitudinal edgeand a recess extending continuously thereunder, a covering layer havinga rigid mounting bar at one end, clamping means for clamping themounting bar in the recess, means recessed in the cylinder fortensioning the opposite end of the covering layer so that the layer isdrawn into a tight bend over the edge of the groove and thence over thesurface of the cylinder, a gripper pad bar extending continuously alongthe edge of the groove, spaced mounts seated in the groove for mountingthe gripper pad bar and for releasably holding it in a normal positionin which it is snugly adjacent the bend in the covering layer, eachmount being of ''''L'''' shape having a radial portion supportivelyengaging the gripper pad bar and having a projecting arm portion atright angles thereto with a pivot at the bend of the ''''L'''', agripper shaft in the groove having a set of grippers cooperating withthe gripper pad bar, means including a cam follower on the shaft forengaging a relatively fixEd cam surface adjacent the cylinder forcyclical operation of the grippers for engaging the leading edges ofsuccessive sheets, means for disengaging the gripper shaft from the camfollower so that the grippers may be retracted well away from thegripper pad bar, the projecting arm portion having a limit stop todefine the normal position and having screw means for retracting thegripper pad bar from its normal position to a position separated fromthe bend of the covering layer to provide a clear radial path so thatupon loosening of the clamping means the mounting bar and covering layermay be removed from the recess clear of the cylinder for replacement byan alternate mounting bar and covering layer.